1. Field of the Invention
The present invention relates to novel 6-nitroprostaglandin derivatives, processes for the production thereof, and the use thereof. It is more particularly concerned with novel compounds of 6-nitroplostaglandin derivatives, which are useful as medicines and also useful as intermediates for other medicine because of their pharmacological activities including platelet aggregation inhibiting activity, blood pressure lowering activity, antiulcerous activity, etc., a process for the preparation thereof, and pharmaceutical compositions which contain any of these compounds as active ingredient and a method of preparing other pharmaceutically active compounds by utilizing them.
2. Description of the Prior Art
Natural prostaglandins are known as local hormones having high biological and pharmacological activities and accordingly many research works have been made on their derivatives. Of all such natural prostaglandins, prostaglandin E.sub.1 is particularly expected to offer clinical applications because of its strong platelet aggregation inhibiting activity and vasodilating activity.
Of recent years 6-oxoprostaglandin E.sub.1, which is deemed to be a derivative of prostaglandin E.sub.1, has been discovered as a biological active metabolite of prostacyclin. 6-Oxoprostaglandin E.sub.1 has strong platelet aggregation inhibiting activity and blood pressure lowering activity resulting from smooth muscle dilating function same as prostacyclin and is expected to have uses in the ingredient of pharmaceutical compositions (European Journal of Pharmacology, Vol. 57, p. 273 (1979); ibid. Vol. 60, p. 245 (1979)). Studies have also been made on various derivatives of 6-oxoprostaglandin E.sub.1 (Japanese Laid-Open Patent Publication No. 44639/79) and furthermore researches on 6-hydroxyprostaglandin E.sub.1 and its derivatives derived from 6-oxoprostaglandin E.sub.1 and its derivatives have been conducted (U.S. Pat. No. 4,131,738).
Also, 6-oxoprostaglandin F.sub.1 .alpha. is known as a metabolite of prostacyclin (Biochem. Biophys. Acta., 574, 182 (1979)). Though 6-oxoprostaglandin F.sub.1 .alpha. is an inactive metabolite, it is expected to be used as a diagnosticum for determining the concentration of prostacyclin in the blood (Brit. J. of Urology, 54, 26 (1982)).